what you see is a "feature". The TListIter save a pointer to
the next object before returning the current one. This so in case
you delete the current object the iteration does not get broken.
The side-effect of this is that you can not add an object to a
list when the iterator is at the last object. If you want to do
what you want don't use an iterator but do:
Use the TObjLink list entries (that wrap the TObject*):
TObjNum *obj;
TObjLink *lnk = list.FirstLink();
while (lnk) {
obj = (TObjNum*)lnk->GetObject();
printf("%d ",obj->GetNum());
if (obj->GetNum()==3) list.Add(new TObjNum(4));
lnk = lnk->Next();
}
Cheers, Fons.
Laurent Aphecetche wrote:
>
> Hi,
>
> Using the TObjNum class defined in the tcollex example ($ROOTSYS/test),
> I am trying to iter over a list, and make the list bigger inside the
> loop :
>
> TList list ;
> TObjNum* obj ;
> TIter next(&list) ;
>
> list.Add(new TObjNum(1)) ;
> list.Add(new TObjNum(2)) ;
> list.Add(new TObjNum(3)) ;
>
> while ( obj = (TObjNum*)next())
> {
> printf("%d ",obj->GetNum()) ;
> if (obj->GetNum()==3) list.Add(new TObjNum(4)) ;
> }
>
> This gives me :
> 1 2 3
> i.e, it lacks the 4.
>
> If I change obj->GetNum()==3 by obj->GetNum()==2 (or 1), it gives me :
> 1 2 3 4
> i.e, correct.
>
> Is this normal ?
>
> Thanks.
>
> --
> APHECETCHE Laurent (mailto:aphecetche@ganil.fr)
> GANIL, B.P. 5027, 14076, Caen Cedex 5, France
> Vox: +33 (0)2 31 45 45 85 - Fax: +33 (0)2 31 45 46 65
> WWW: http://ganp03.in2p3.fr/nof/ & (perso.)
> http://www.mygale.org/~p0mp0n
-- Org: CERN, European Laboratory for Particle Physics. Mail: 1211 Geneve 23, Switzerland Phone: +41 22 7679248 E-Mail: Fons.Rademakers@cern.ch Fax: +41 22 7677910